Methods and devices for occluding a patient&#39;s ascending aorta

ABSTRACT

An aortic occlusion catheter has a blood return lumen for returning oxygenated blood to a patient and an occluding member for occluding the patient&#39;s ascending aorta. The blood return lumen has openings on both sides of the occluding member for infusing oxygenated blood on both sides of the occluding member.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending application Ser. No.08/831,102 filed Apr. 1, 1997, now U.S. Pat. No. 5,755,687.

BACKGROUND OF THE INVENTION

The present invention is directed to methods and devices for occluding apatient's ascending aorta and returning oxygenated blood to the patientwhen the patient is supported by a bypass system. The invention isparticularly useful when performing surgery on the heart and greatvessels.

In conventional open heart surgery, the patient's heart is accessedthrough a large opening in the patient's chest, such as a mediansternotomy. With the patient's heart exposed, various catheters,cannulae and clamps are applied directly to the patient's heart andgreat vessels. Blood is withdrawn from the patient through a venouscannula and returned to the patient through an arterial return cannulawhich is typically inserted through a pursestring suture in theascending aorta. The heart is arrested by infusing a cardioplegic fluidinto the ascending aorta with a needle. The ascending aorta is typicallyoccluded with an external cross-clamp around the ascending aorta toisolate the coronary arteries from the remainder of the arterial system.

Recent developments in cardiac surgery have provided cannulae andcatheters for occluding a patient's ascending aorta, returningoxygenated blood to the patient, and delivering cardioplegic fluid tothe patient without requiring direct access to the patient's heart. Suchsystems are described in U.S. Pat. Nos. 5,584,803, 5,478,309 and Re.35,352. The devices and methods described in these patents enablesurgeons to perform various procedures on the patient's heart and greatvessels, such as bypass grafting and valve replacements, withoutrequiring a large opening in the patient's chest. Such procedures reducethe pain and trauma suffered by the patient as compared to traditionalopen-heart procedures.

Another advantage of the systems described in U.S. Pat. Nos. 5,584,803,5,478,309 and Re. 35,352 is that occlusion of the aorta is accomplishedwith a balloon positioned in the aorta rather than an external clamparound the aorta. Use of a balloon to occlude the ascending aorta mayreduce the amount of emboli released into the bloodstream as compared toexternal cross-clamps thereby reducing stroke incidents.

Although the systems described above enable a wide range of surgicalprocedures on a stopped heart, positioning of the aortic occlusionballoon is often challenging since the balloon must be positioned in arelatively small space between the aortic valve and brachiocephalicartery. Inadvertent occlusion of the brachiocephalic artery is dangeroussince the right carotid artery, which branches off the brachiocephalicartery and provides blood to the patient's brain, would also not receiveoxygenated blood. Positioning of the balloon is particularly challengingwhen performing aortic valve procedures since the balloon must bepositioned far enough from the aortic valve to permit the surgeon toperform the procedure on the aortic valve without interference from theballoon.

Thus, an object of the present invention is to provide an aorticocclusion catheter having an occluding member which may be easilypositioned within a patient's ascending aorta.

SUMMARY OF THE INVENTION

The present invention provides an aortic occlusion catheter and methodof occluding a patient's ascending aorta and delivering oxygenated bloodto the patient from a bypass system. The aortic occlusion catheter isinserted through a penetration in the patient's arterial system andpassed through the junction between the brachiocephalic artery andascending aorta. In a preferred embodiment, the aortic occlusioncatheter preferably enters the patient's arterial system through apenetration in the axillary or subclavian artery.

The aortic occlusion catheter has an occluding member which ispositioned in the ascending aorta and expanded to occlude the patient'sascending aorta thereby isolating the coronary arteries from the rest ofthe patient's arterial system. The occluding member, which is preferablya balloon, is preferably attached to the catheter shaft along a portionbetween proximal and distal ends of the occluding member. When theoccluding member is expanded, the occluding member expands toward oneside of the shaft. In a preferred embodiment, the expanding side of theoccluding member is positioned to expand toward the aortic valve.

The aortic occlusion catheter also has a blood flow lumen having firstand second openings for returning oxygenated blood to the patient. Thefirst and second openings are on opposite sides of the occluding memberso that oxygenated blood is delivered to both sides of the occludingmember. One of the openings provides oxygenated blood to arteriessuperior to the junction between the brachiocephalic artery and theaortic arch while the other opening provides oxygenated blood to therest of the body. An advantage of providing openings on both sides ofthe occluding member is that occlusion of the brachiocephalic arterydoes not pose a risk to the patient since oxygenated blood is deliveredto both sides of the occluding member. Another advantage of the aorticocclusion catheter is that the occluding member is easily positioned farfrom the aortic valve thereby maximizing the working space forperforming aortic valve procedures.

The aortic occlusion catheter also preferably includes two pressurelumens for measuring pressure on both sides of the occluding member.Although two pressure lumens are preferred, only one pressure lumen maybe necessary. The pressure lumens are coupled to a pressure monitor formeasuring the blood pressure on both sides of the occluding member. Thepressure monitor is used to prevent excessively high or low bloodpressures and, in particular, excessively high blood pressure in thecarotid arteries.

These and other features will become apparent from the followingdescription of the preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial cross-sectional view of a patient's heart andvascular system which illustrates an aortic occlusion catheter of thepresent invention together with a bypass system.

FIG. 2 is an enlarged view of the aortic occlusion catheter of FIG. 1.

FIG. 3 is a side view of the aortic occlusion catheter of FIGS. 1 and 2.

FIG. 4 is a cross-sectional view of the aortic occlusion catheter atline A--A of FIG. 3.

FIG. 5 is a cross-sectional view of another aortic occlusion catheter.

FIG. 6 is a cross-sectional view of yet another aortic occlusioncatheter.

FIG. 7 is a longitudinal cross-sectional view illustrating a method offorming a wire-reinforced blood flow lumen, FIG. 8 is a longitudinalcross-sectional view of the structure of FIG. 7 after heating.

FIG. 9 is a longitudinal cross-sectional view illustrating a method offorming a second wire-reinforced blood flow lumen, FIG. 10 is alongitudinal cross-sectional view of the structure of FIG. 9 afterheating.

FIG. 11 is a cross-sectional view of the aortic occlusion cathetershowing the method of adding pressure lumens and an inflation lumen tothe wire reinforced blood flow lumen for the aortic occlusion catheterof FIG. 4.

FIG. 12 is a cross-sectional view of the aortic occlusion cathetershowing the method of adding pressure lumens and an inflation lumen tothe wire reinforced blood flow lumen for the aortic occlusion catheterof FIG. 5.

FIG. 13 is a cross-sectional view of the aortic occlusion cathetershowing the method of adding pressure lumens and an inflation lumen tothe wire reinforced blood flow lumen for the aortic occlusion catheterof FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a system for arresting a patient's heart andmaintaining circulation of oxygenated blood through the patient isshown. The system is shown for the purposes of illustrating an aorticocclusion catheter 2 in accordance with the present invention and othersystems, catheters, cannulae and the like may be used with the inventionwithout departing from the scope of the invention.

Blood is withdrawn from the patient through a venous cannula 4 which isinserted into the patient's vascular system at any suitable location.FIG. 1 illustrates the venous cannula 4 passing through the femoral veinand into the patient's right atrium. Blood is also withdrawn from thepatient through a venting catheter 6 which vents the patient's heartthrough the pulmonary vasculature. The venting catheter 6 extendsthrough the internal jugular vein and tricuspid and pulmonary valves sothat a distal end 8 is in the pulmonary artery. Although it is preferredto provide the venting catheter 6, venting of the heart may also beaccomplished with any other device such as a needle penetrating thepulmonary artery.

Blood withdrawn through the venous cannula 4 and venting catheter 6 isdirected to a bypass system 10 which preferably includes a pump forpumping oxygenated blood through the patient. The bypass system 10 mayalso include one or more of the following; a heat exchanger, oxygenator,filter, bubble trap, and cardiotomy reservoir. The bypass system 10preferably includes an external oxygenator, however, the patient's ownlungs may also be used to oxygenate the blood.

After the blood passes through the bypass system 10, oxygenated blood isreturned to the patient from the bypass system 10 through the aorticocclusion catheter 2 which is described in greater detail below. Theaortic occlusion catheter 2 has an occluding member 12, which ispreferably a balloon, for occluding the patient's ascending aorta.Occlusion of the ascending aorta isolates the coronary arteries from theremainder of the arterial system to prevent the heart from receivingoxygenated blood and starting prematurely before completion of thesurgical procedure. A source of inflation fluid 14, which is preferablya syringe filled with saline solution, is used to inflate the occludingmember 12.

The patient's heart may be arrested using any method and a preferredmethod is to use a cardioplegic fluid. Cardioplegic fluid may beadministered antegrade or retrograde through the coronary sinus. Thesystem shown in FIG. 1 includes both antegrade and retrograde perfusion,however, only one type of perfusion may be necessary. The cardioplegicfluid may be any type of cardioplegic fluid and a preferred cardioplegicfluid is blood cardioplegia which is a mixture of crystalloidcardioplegia and blood. A source of cardioplegic fluid 16 draws bloodfrom the bypass system 10 for mixing with a cardioplegic agent to formthe cardioplegic fluid. Cardioplegic fluid is introduced antegrade witha needle 18 and retrograde with a coronary sinus catheter 20. Thecoronary sinus catheter 20 passes through the internal jugular vein,into the right atrium and into the coronary sinus 20. The coronary sinuscatheter 20 preferably has a balloon (not shown) for occluding thecoronary sinus. Although it is preferred to endovascularly advance thecoronary sinus catheter through a peripheral vein, the coronary sinuscatheter 20 may also simply pass through an opening in the right atrium.

Referring now to FIGS. 1-3, the aortic occlusion catheter 2 has a bloodreturn lumen 22 for returning oxygenated blood to the patient from thebypass system 10. The blood return lumen 22 has proximal openings 24 anddistal openings 26 for infusing oxygenated blood from the bypass system10 on both sides of the occluding member 12. Delivery of oxygenatedblood through the proximal openings 24 provides oxygenated blood toarteries downstream of the brachiocephalic artery such as the axillary,subclavian and carotid arteries. Delivery of oxygenated blood throughthe distal openings 26, which includes the open end 28 of the catheter2, provides oxygenated blood to the rest of the body. The proximalopenings 24 preferably have a diameter of between 0.02 and 0.2 inch andmore preferably 0.04 inch and a preferred number of proximal openings 24is between 3 and 60. The total area of the proximal openings 24 ispreferably about 5% to 30% and more, preferably about 10% of the area ofthe distal openings 26 so that more oxygenated blood passes through thedistal openings 26 since a larger portion of the patient's arterialsystem is distal to the occluding member 12. The blood return lumen 22terminates at a conventional barbed connection 30 suitable forconnection to the bypass system 10. The blood return lumen 22 ispreferably coated with a conventional athrombogenic coating such asbenzalkonium heparin to minimize damage to the blood. The outside of thecatheter 2 may also be coated with a lubricious coating to facilitateintroduction of the catheter 2 into the patient. Any suitable coatingmay be used and a preferred coating is polyvinyl pyrrolidone.

Still referring to FIGS. 1-3, the aortic occlusion catheter 2 preferablyenters the patient's aortic arch from the brachiocephalic artery andenters through a penetration in the subclavian, axillary, or brachialarteries. FIG. 1 shows the aortic occlusion catheter 2 passing through apenetration in the axillary artery and passing through the subclavianand brachiocephalic arteries. When inserting the aortic occlusioncatheter 2 through the penetration and advancing the catheter 2 throughthe patient's arteries, an obturator 32 is positioned in the bloodreturn lumen 22 to provide an atraumatic distal end. Using fluoroscopy,a guidewire 23 is first passed through the artery. The aortic occlusioncatheter 2 and accompanying obturator 32 are then passed together overthe guidewire 23 to position the catheter as shown in FIG. 2. Once thecatheter 2 is in position, the obturator 32 and guidewire 23 areremoved. The catheter 2 is then primed to remove all air by permittingblood to flow through the catheter 2 and the catheter 2 is thenconnected to the bypass system 1

As shown in FIGS. 1 and 2, the aortic occlusion catheter 2 is positionedto occlude or partially occlude the brachiocephalic artery. This wouldnormally present a dangerous condition, however, the proximal openings24 provide oxygenated blood to arteries downstream of thebrachiocephalic artery such as the subclavian, carotid and axillaryarteries so that even complete occlusion of the brachiocephalic arteryis not a problem. Thus, an advantage of the aortic occlusion catheter 2of the present invention is that the occluding member 12 is readilypositioned away from the patient's aortic valve so that contact with theaortic valve is not a problem while also eliminating the risk thatocclusion of the brachiocephalic artery will cut off blood to thecarotid artery. The aortic occlusion catheter 2 is particularly usefulwhen performing aortic valve procedures since the occluding member 12 ispositioned far from the aortic valve.

Referring to FIGS. 1-4, the aortic occlusion catheter 2 has first andsecond pressure lumens 34, 36 coupled to a pressure monitor 38 formonitoring pressures proximal and distal to the occluding member 12. Thefirst and second pressure lumens 34, 36 have first and second pressureports, 35, 37, respectively. Although it is preferred to provide thepressure lumens 34, 36, pressure sensing may be accomplished by anyother method such as with pressure transducers. The pressure monitor 38is used to prevent excessively high or low blood pressure whendelivering blood through the proximal and distal openings 24, 26. If,for example, the distal openings 26 are occluded or obstructed, all ofthe blood would be forced through the proximal openings 24 which maycreate undesirably high pressures in the brachiocephalic and carotidarteries. A pressure relief valve (not shown) may be provided to preventexcessive pressures when delivering blood to the patient. Alternatively,a pressure sensor may be coupled to the bypass system 10 so that thedelivery of oxygenated blood is regulated to prevent excessivepressures. Although it is preferred to provide both the first and secondpressure lumens, 34, 36, only one of the lumens 34, 36 may also beprovided such as only the first lumen 34. The pressure lumens 34, 36have connectors 33 suitable for connection to the pressure monitor 38.

Referring to FIG. 4, a cross-sectional view of the aortic occlusioncatheter 2 is shown. The pressure lumens 34, 36 are positioned oppositean inflation lumen 38 which is used to inflate the occluding member 12.The aortic occlusion catheter 2 is preferably reinforced with a wire 39which is wound helically around catheter shaft 40. FIG. 5 shows analternative construction in which the pressure lumens 34, 36 andinflation lumen 38 are positioned adjacent one another while FIG. 6shows the pressure lumens 34, 36 and inflation lumen 38 spaced aroundthe periphery of the aortic occlusion catheter 2. The method of formingthe catheter 2 is described in greater detail below.

Referring again to FIGS. 1-3, the occluding member 12 is preferably aninflatable balloon which may be made of any suitable elastic orinelastic material and a preferred material is polyurethane. Theoccluding member 12 is preferably bonded to the shaft 40 along a side 41extending between proximal and distal ends 42, 44 of the occludingmember 12. The resulting occluding member 12 expands toward one side ofthe shaft 40 in the manner shown in FIGS. 1-3. Although it is preferredto bond the side 41 of the occluding member 12 to the shaft 40, theoccluding member 12 may also be bonded to the shaft 40 only at theproximal and distal ends 42, 44 so that the occluding member 12 expandsin all directions around the shaft 40. The inflation lumen 38, which hasan inflation opening 46 for inflating the occluding member 12, has aconnector 48 suitable for connection to the source of inflation fluid 14for inflating the occluding member 12.

Referring to FIG. 2 and FIG. 4, the shaft 40 is preferably reinforcedwith the wire 39. Although it is preferred to provide a wire-reinforcedconstruction for the shaft 40, the shaft 40 may have any other suitableconstruction such as an extrusion. The catheter 2 is preferably veryflexible with the preferred shape being substantially straight when inan unbiased condition. Alternatively, the distal end of the catheter 2may be slightly curved in the manner shown at dotted line 50 in FIG. 3.

The method of constructing the wire-reinforced shaft 40 is now describedwith reference to FIGS. 7-10. The method begins with construction of areinforced tube 52. A first tube 54 is mounted on a mandrel (not shown)and the wire 39 is wrapped in a helical fashion around the first tube 54in the manner shown in the longitudinal cross-section of FIGS. 7 and 9.The wire 39 is preferably a stainless steel wire having a diameter ofbetween 0.001 and 0.015 inch and more preferably 0.007 inch. A secondtube 56 is then positioned over the wire 39 and the first and secondtubes 54, 56 are encased in a heat shrink tube (not shown) and heated sothat the first and second tubes 54, 56 and wire 39 form the reinforcedtube 52 shown in FIGS. 8 and 10, respectively. The first and secondtubes 54, 56 preferably have a thickness of between 0.001 and 0.010 inchand more preferably 0.003 inch. The first and second tubes 54, 56 may bemade of any suitable material and a preferred material is polyurethane.

The wire 39 is preferably wrapped around the second tube 56 with alarger spacing around portions 58 of the shaft 40 where the proximal anddistal openings 24, 26 will be formed so that the proximal and distalopenings 24, 26 may be formed without cutting through the wire 39. FIGS.7 and 8 illustrate a uniform spacing of about 0.040 inch betweenadjacent portions of the wire 39 at the portions 58 where the proximaland distal openings 24, 26 will be formed. FIGS. 9 and 10 show aconstruction having alternating small and large spacing with theproximal and distal openings 24, 26 being formed in the portions 58having the large spacing. Yet another method is to provide a uniformspacing throughout the shaft 40 with the spacing being large enough topermit forming the proximal and distal openings 24, 26 without cuttingthrough the wire 39. FIGS. 8 and 10 illustrate slight depressionsbetween adjacent portions of the wire 39 which are eventually filledwhen the pressure lumens 34, 36 and inflation lumen 38 are added asdescribed below.

After formation of the reinforced tubes 52 shown in FIG. 8 and 10, thefirst and second pressure lumens 34, 36 and the inflation lumen 38 arebonded to the reinforced tube 52. Referring to FIGS. 11-13, the methodof constructing the cross-sections shown in FIGS. 4-6, respectively, isshown. FIG. 11 shows the pressure lumens 34, 36 carried together by aD-shaped extrusion 60 which is positioned opposite another D-shapedextrusion 62 for the inflation lumen 38. FIG. 12 shows the pressurelumens 34, 36 and inflation lumen 38 both being carried by a singleD-shaped extrusion 64. FIG. 13 shows the pressure lumens 34, 36 andinflation lumen 38 each carried by a separate D-shaped extrusions 66,68, 70, respectively, with the lumens 34, 36, 38 being spaced 120E apartfrom one another.

An outer tube 72 is positioned over the pressure lumens 34, 36 andinflation lumen 38. The outer tube 72 is preferably inflated and thereinforced tube 52, pressure lumens 34, 36, and inflation lumen 38 arethen positioned inside the outer tube 72. The outer tube 72 is thendeflated so that it contracts around the pressure lumens 34, 36,inflation lumen 38 and reinforced tube 52 in the manner shown in FIGS.11-13. The outer tube 72 is preferably made of the same material as thefirst and second tubes 54, 56 and has a thickness of between 0.001 and0.010 inch and more preferably 0.003 inch. A heat shrink tube (notshown) is positioned over the outer tube 72 and the entire structure isheated to form the integrated structures of FIGS. 4-6. The pressureports 35, 37 in the pressure lumens 34, 36, opening 46 in the inflationlumen 38, and proximal and distal openings 24, 26 in the blood returnlumen 22 are then formed. An advantage of adding the pressure lumens 34,36 and inflation lumen 38 to the outside of the blood return lumen 22 isthat the pressure ports 35, 37 and opening 46 in the inflation lumen 38do not need to be cut through the wire 39.

The aortic occlusion catheter 2 preferably has a soft tip 74 which ismade of polyurethane and preferably doped with a radiopaque material sothat the position may be visualized using fluoroscopy. The soft tip 74is bonded to the end of the shaft 40 after forming the reinforced tube52 so that the tip 74 does not include the wire 39 reinforcing.Radiopaque markers 76 are provided on both sides of the occluding member12 to further aid in visualizing and positioning the catheter 2 andoccluding member 12 . The distal openings 26 are also formed through thesoft tip 74.

While the above is a preferred description of the invention, variousalternatives, modifications and equivalents may be used withoutdeparting from the scope of the invention. For example, the occludingmember 12 can be an expandable member other than a balloon, theorientation of the aortic occlusion catheter 2 may be reversed with theaortic occlusion catheter 2 passing through another artery, such as theleft subclavian artery, with the distal end extending into thebrachiocephalic artery, and the aortic occlusion catheter 2 may alsoinclude a lumen for delivering cardioplegic fluid to the patient'sascending aorta and venting the aortic root. Thus, the above descriptionshould not be taken as limiting the scope of the invention which isdefined by the claims.

What is claimed is:
 1. A catheter system for occluding a patient'sascending aorta and returning oxygenated blood to the patient from abypass system, comprising:a shaft having a blood flow lumen, the bloodflow lumen being sized to provide full bypass support for a patient; anoccluding member mounted to the shaft, the occluding member having acollapsed shape and an expanded shape, the expanded shape being sizedand configured to occlude a patient's ascending aorta; a venous cannulahaving a blood withdrawal lumen; and a bypass system coupled to theblood withdrawal lumen for receiving blood from the patient, the bypasssystem also being coupled to the blood flow lumen for returning blood tothe patient; the shaft also having first and second openings in fluidcommunication with the blood flow lumen, the first opening beingpositioned proximal to the occluding member and the second opening beingpositioned distal to the occluding member.
 2. The catheter system ofclaim 1, wherein:the occluding member is attached to the shaft at aproximal portion and a distal portion, the occluding member also beingattached to the shaft along a portion extending between the proximal anddistal portions.
 3. The catheter system of claim 1, wherein:the shaftincludes a reinforcing wire.
 4. A catheter system for occluding apatient's ascending aorta and returning oxygenated blood to the patientfrom a bypass system, comprising:a shaft having a blood flow lumen, theblood flow lumen being sized to provide full bypass support for apatient; and an occluding member mounted to the shaft, the occludingmember having a collapsed shape and an expanded shape, the expandedshape being sized and configured to occlude a patient's ascending aorta;means for sensing a pressure on a side of the occluding member; theshaft also having first and second openings in fluid communication withthe blood flow lumen, the first opening being positioned proximal to theoccluding member and the second opening being positioned distal to theoccluding member.
 5. The catheter system of claim 4, furthercomprising:means for sensing a pressure on another side of the occludingmember.